There is a switch device including a button to be pushed in order to drive a target object. For example, a switch device as described in JP-A-2004-314806, JP-A-2011-169180, JP-A-2011-60626, and JP-A-2011-27085 is incorporated in a vehicle security system in which a travel driving source (an engine or the like) of a vehicle is started or stopped on the basis of wireless communication between an in-vehicle device and a portable device which is carried by a user so as to prevent the vehicle from being stolen. In the vehicle security system, the traveling driving source is started or stopped when the portable device is successively authenticated through the wireless communication between the in-vehicle device and the portable device and the button of the switch device provided in a vehicle cabin is pushed.
The switch device as in JP-A-2004-314806, JP-A-2011-169180, JP-A-2011-60626, and JP-A-2011-27085 includes a slider, a movable contact point, a substrate provided with a fixed contact point, an elastic member, a coil antenna, and a tube-shaped holder or a case that accommodates those described above in addition to the button. The button and the slider are held in the holder or the case such that the button and the slider can slide in a pushing direction of the button or in a direction opposite to the pushing direction. The slider slides when the button is pushed. The elastic member urges the slider and the movable contact point toward the button.
When the button of the switch device is pushed, the slider slides and the movable contact point comes into contact with the fixed contact point. When the pushed button is released, the slider slides toward the button due to an elastic force from the elastic member so that the button returns to a regular position and the movable contact point is separated from the fixed contact point.
As an auxiliary communication method for a case where the communication cannot be performed with a battery in the portable device having been consumed, an activation electric wave that operates the portable device is transmitted from the coil antenna. When the portable device receives the activation electric wave transmitted from the coil antenna, the portable device communicates with the in-vehicle device by using an electromotive force generated by an internal coil.
In JP-A-2004-314806, the coil antenna is disposed in the vicinity of the button. However, according to this configuration, the size of the switch device in a radial direction of the button becomes large. In JP-A-2011-169180, JP-A-2011-60626, and JP-A-2011-27085, the coil antenna is disposed inside the button so as to achieve reduction in size of the switch device.